JPH019036Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an improvement of a wire rope type control rod drive device for inserting and withdrawing control rods into and out of a nuclear reactor to control the output of a nuclear reactor.

In order to control the nuclear fission reaction within a nuclear reactor, control rods filled with neutron absorbing material are inserted into and withdrawn from the reactor, but they must be able to be inserted and withdrawn reliably under any circumstances.

Figure 1 shows a conventional control rod drive device.
A wire rope 3 connected to the control rod 1 via a connecting fitting 2, a drum 4 that winds up and unwinds the wire rope 3, a drive shaft 6 to which the drum 4 and transmission gear 5 are attached, and a drive shaft 6 that rotates. It is comprised of a ball bearing 7 that supports freely, a drive motor 9 equipped with a pinion 8 that meshes with a transmission gear 5, a guide tube 11 that guides the control rod 1 into the reactor core 12, and the like. 10 is a position detection mechanism that detects the position of the control rod 1 in terms of rotation angle.

In the control rod drive device configured in this way, the drive motor 9 rotates the drum 4 and winds up and lowers the wire rope 3, so that the control rods 1 are moved up and down to the appropriate position in the reactor core 12. occupy position and control nuclear reactions within the reactor. The guide tube 11 is for accurately guiding the control rod 1 into the reactor core 12, and plays an important role in this wire rope type. The upper end of the guide tube 11 is a drive part flange 13
The lower end is inserted into the reactor core. Further, although the control rod 1 is suspended by a wire rope 3, the guide tube 11 can prevent lateral vibration even when a lateral load is applied due to an earthquake or the like. However, while having high rigidity against lateral loads is effective in preventing lateral vibration, it may cause misalignment between the core 12 and the control rod drive device due to earthquakes, displacement or deformation due to heat in the core 12, neutron irradiation, etc. When this occurs, the stress in the guide tube 11 becomes large, and the allowable misalignment amount has to be reduced.
If a large misalignment occurs, the guide tube 11 will yield and deform, which will hinder the subsequent insertion and withdrawal of the control rod 1 and may cause the reactor to run out of control.

The purpose of the present invention is to increase the allowable misalignment between the core and the control rod drive device without reducing the rigidity of the guide tube itself, and to obtain a reliable control rod drive device.

An embodiment of the present invention will be described below with reference to the drawings.

2 and 3 are enlarged explanatory views of the guide tube attachment portion of the present invention, and the same parts as in FIG. 1 are given the same reference numerals, and detailed explanation thereof will be omitted. The guide tube 11 has a cylindrical shape, and a fastening bolt 1 is attached to the control rod drive unit flange 13.
4, an elastic body 15 such as a disc spring is installed between the drive part flange 13 and the guide pipe flange 11a.
is provided. The rest is as shown in Figure 1.

Next, the operation will be explained using FIGS. 4 and 5.

If the core 12 and the control rod drive device are misaligned with respect to the vertical line 16 due to the above-mentioned reasons, etc.,
While the deformation mode of the conventional guide tube was a cantilever beam, the attachment part of the guide tube flange of this embodiment has an elastic body 15 interposed therebetween so that it can be expanded and contracted, so it can be made to be close to a sliding joint. . Here, the misalignment amount δ and the deflection amount Δ of the elastic body 15, that is, the guide pipe flange 11
Numerically considering the amount of movement of a, in a general control rod drive device, the length L of the guide tube 11 is approximately 4500 mm, and the pitch circle D of the fastening bolt 14 is approximately 200 mm, so the above-mentioned accidents etc. If the allowable maximum misalignment amount δ is set to about 50 mm with a margin in mind, then δ≒L/DΔ, so Δ≒D/Lδ=200/4500×50≒2.2 mm.Therefore, the elastic body 15 is 2.2 mm. A large misalignment amount δ that reaches about 50 mm with a small amount of deflection Δ of about mm
can be tolerated. Further, the stress in the guide tube is only a moment due to the reaction force of the elastic body 15, and it is possible to reduce the generated stress while increasing the allowable misalignment amount δ. It should be noted that the elastic body 15 must be preloaded to a certain degree in case of an earthquake, and the guide tube will not move due to fluid vibration or external vibration, so the control rod can move smoothly inside the guide tube. Can move up and down.

In this embodiment, the elastic body 15 is a disc spring, but a coil spring, a wave spring, etc. can also have the same effect, and the type of elastic body is not limited. Further, in this embodiment, the elastic body 15 is provided for each fastening bolt 14, but the elastic body 15 may be provided on the entire surface between the flanges. As described above, according to the present invention, the guide tube is attached to the drive unit flange by bolts via an elastic body such as a disc spring, a wave spring, or a coil spring, thereby simplifying the structure and connecting the core and control rods. It becomes possible to increase the allowable misalignment amount of the drive device, smooth the extraction and insertion of the control rod, and obtain a highly reliable control rod drive device.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view of a conventional control rod drive device;
The figure is an enlarged cross-sectional view of the guide tube attachment part of one embodiment of the control rod drive device of the present invention, Figure 3 is a cross-sectional view taken along the - line in Figure 2, and Figure 4 is a cross-sectional view of the guide tube attachment part of an embodiment of the control rod drive device of the present invention. The working state diagram, FIG. 5, is an explanatory diagram showing numerically the relationship between the amount of misalignment δ and the amount of deflection Δ in FIG. 4. DESCRIPTION OF SYMBOLS 1... Control rod, 3... Wire rope, 4... Drum, 9... Drive motor, 11... Guide tube, 12
... Reactor core, 13 ... Drive section flange, 14 ... Fastening bolt, 15 ... Elastic body.

Claims (1)

[Scope of utility model registration request] A control rod drive device consisting of a drive motor, a drum driven by the drive motor, a control rod connected to a wire rope wound around the drum, and a flanged guide tube that guides the control rod to a predetermined position in the reactor core. The guide tube flange is attached to the drive section flange by bolt connection with an elastic body such as a disc spring, a wave spring, or a coil spring being telescopically interposed so that the attachment section of the guide tube flange can be tilted. Control rod drive.